1. Field
Aspects of the present invention generally relate to a printing method, a printing apparatus, and a computer-readable storage medium.
2. Description of the Related Art
In an ink jet printing apparatus, drying of ink in or around nozzles of a print head may cause thickening of the ink, leading to an ejection failure. A method known in the art for preventing such a failure is to perform an operation, called “preliminary ejection”, of ejecting thickened ink to an ink receiver including an ink absorbing member prior to image printing. In a serial printer configured in such a manner that a print head is moved relative to a printing medium to print an image, preliminary ejection is typically executed in a predetermined position outside the printing medium.
A known full multiple printer is configured in such a manner that a plurality of print heads are arranged across the entire width of a printing medium and the printing medium is conveyed relative to the print heads, which are fixed, to print an image. In the full multiple printer, the execution of only preliminary ejection outside a printing medium leads to a long time interval between the preliminary ejections. Disadvantageously, it is difficult to maintain proper ejection performance. In addition, image printing has to be suspended and the print heads or an ink receiver has to be moved, leading to low throughput. Another known way of preliminary ejection, called “paper preliminary ejection”, is to preliminarily eject ink onto a printing medium to be subjected to image printing. After start of printing an image on a printing medium, the paper preliminary ejection and the printing can be performed simultaneously without suspension of the printing. Thus, the paper preliminary ejection achieves a good balance between maintaining high quality of a printed image and suppressing a reduction in throughput.
Since the paper preliminary ejection is performed such that ink is ejected onto a printing medium on which an image is to be formed, dots formed on the printing medium may be visible to a user depending on the density or amount of ink, resulting in a reduction in printing quality. One of methods addressing this issue is described in U.S. Patent Application Publication No. 2009/0267981. According to this method, when paper preliminary ejection is performed on a color image, data for the paper preliminary ejection is deleted. This suppresses an increase in dot diameter, thus making dots formed by the paper preliminary ejection less visible. Furthermore, U.S. Pat. No. 5,903,288 describes a method of forming color-ink dots for paper preliminary ejection such that the color-ink dots are superposed on black-ink dots in accordance with data indicating that black ink is to be ejected to an area facing nozzles requiring preliminary ejection in a print head.
U.S. Patent Application Publication No. 2009/0267981 and U.S. Pat. No. 5,903,288 describe the methods of ejecting ink for paper preliminary ejection to a position based on ejection data in an image to be printed. In an area where dots are not formed in a printed image, the visibility of dots formed by paper preliminary ejection is not reduced. In particular, if the dots formed by paper preliminary ejection significantly differ in lightness from a printing medium or an image formed around the dots, the dots formed by the paper preliminary ejection will be more visible.